“We must … continue to go into space for the future of humanity,” Hawking said during a Tuesday speech at Oxford University Union. “I don’t think we will survive another 1,000 years without escaping beyond our fragile planet.”

The renowned theoretical physicist offered that thousand-year deadline because he says the likelihood of disaster compounds over time, and provides humankind a wide enough window to develop technology such that when the “big one” comes, it won’t be utterly devastating.

“Although the chance of a disaster to planet Earth in a given year may be quite low, it adds up over time, and becomes a near certainty in the next thousand or ten thousand years,” said Hawking. “By that time we should have spread out into space, and to other stars, so a disaster on Earth would not mean the end of the human race.”

Still, Hawking said, his prediction assumes that humanity survives the effects of climate change, the ravages of artificial intelligence and the rise of nuclear terrorism during the next century. He would later tell the audience that those who devour Earth’s resources will only hasten the arrival of that cataclysmic end.

To avoid that future, Hawking concluded that our species’ best hope for survival lies in the stars — and space agencies and entrepreneurs tend to agree.

For instance, SpaceX CEO and founder Elon Musk hopes to conduct a manned mission to Mars within six years. Likewise, NASA has been on the hunt for Earth-like planets since 2009, and has discovered more than 4,600 “candidate” planets and another 2,300 or so confirmed planets with the potential for human colonization.

“The first exoplanet orbiting another star like our sun was discovered in 1995,” NASA wrote. “Exoplanets, especially small Earth-size worlds, belonged within the realm of science fiction just 21 years ago. Today, and thousands of discoveries later, astronomers are on the cusp of finding something people have dreamt (sic) about for thousands of years.”

Hawking ended on a positive note, saying that even though the challenges ahead are immense, it is a “glorious time to be alive and doing research into theoretical physics. Our picture of the universe has changed a great deal in the last 50 years, and I am happy if I have made a small contribution.”